Is a blower door test required for new construction?

Yes, a blower door test is required for new construction in most states that have adopted recent energy codes, specifically the International Energy Conservation Code 2012 and later versions. The 2012 IECC required a blower door test with maximum 5 air changes per hour at 50 Pascals ACH50 for climate zones 1 and 2 and 3 ACH50 for zones 3 through 8. The 2015, 2018, and 2021 IECC tightened this to 5 ACH50 for zones 1-2 and 3 ACH50 for zones 3-8, and some states adopting 2021 IECC require even tighter. This requirement applies to new residential construction and additions where new envelope is created. The test must be performed by a certified third party tester with calibrated equipment and results reported to code official before certificate of occupancy is issued. Additionally, many utility programs like Energy Star for new homes require blower door testing below 4 ACH50. The purpose is to ensure builders are actually air sealing and not leaving large leaks that cause energy waste, comfort problems, and moisture issues. If a home fails, builder must air seal and retest. So if you are building new, expect blower door testing to be mandatory in most jurisdictions.